1. Field of Invention
The present invention relates to a distal protection and delivery system that is placed using a guidewire in a tubular member of the human body that has a lesion or injury that requires diagnosis or therapy without allowing emboli to be released downstream. More specifically the invention relates to an intravascular system that is placed percutaneously into a blood vessel of the body that has a lesion to be treated by angioplasty, stent placement, a therectomy, thrombectomy, or other therapy, or diagnosis. The blood vessel to be treated can include the coronary, carotid, femoral, popliteal, or other vessel having a vascular lesion that requires interventional treatment. During treatment of such blood vessels, embolic debris can be embolized downstream causing blockage to distal capillary beds and arterioles. This vascular blockage results in reduced tissue perfusion and compromised tissue function. Placement of a distal protection device downstream of the treatment site can allow emboli to be collected and removed from the body rather than causing embolic injury. The distal protection and delivery system of the present invention includes a guidewire that can navigate tortuous blood vessel to reach the vessel lesion as easily as other standard prior art guidewires. The system also includes a filter assembly that is not attached to the guidewire and therefore can be delivered with an introducer to a site distal to the vessel lesion separately from the guidewire.
2. Description of Prior Art
Distal protection devices have been used in tubular vessels of the body including arteries and veins in order to prevent emboli such as thrombi, plaque, and other embolic debris from drifting downstream and causing distal tissue injury. Most distal protection devices have filters that are attached directly to the distal portion of a guidewire or to a portion of a catheter. Filter devices can sometimes be used during surgery, during percutaneous interventional procedures, and also filters can be implanted permanently into the body. The device of the present invention is intended for use during angioplasty or other interventional use.    Distal protection devices having a filter attached to a guidewire include the device of Tsugita (U.S. Pat. No. 5,910,154), Kerr (U.S. Pat. No. 5,941,896), Ruiz (U.S. Pat. No. 5,928,261), Reger (U.S. Pat. No. 5,160,342), and Ginsburg (U.S. Pat. No. 4,873,978). Tsugita describes a filter apparatus for treating stenosed blood vessels. The guidewire has a filter attached to it for capturing loose embolic material. The filter has an expansion frame having a filter mesh attached to it. One major difficulty with this type of device is that the guidewire cannot traverse a tortuous pathway in a blood vessel with a filter attached and with a holding tube surrounding the filter to hold it in the smaller diameter configuration. The filter along with the holding tube are very stiff and will restrict the ability of the guidewire from making tight turns into small vessels. Kerr describes a conically shaped filter with a porous fabric or a fine fiber mesh. Emboli from an angioplasty procedure are trapped by the filter and connecting loops can be drawn together to hold the emboli. This device shares similar disadvantages to the device of Tsugita. Ruiz describes a removable vascular filter and apparatus that is expanded within the vessel and held in place by a coiled-sheet stent portion with a magnetic band. When the coiled-sheet stent portion is released within the blood vessel, it uncoils to engage a wall of the vessel and deploys the filter element across the flow path. This device would be very stiff due to its configuration and would have much difficulty traversing a tortuous vascular pathway. Reger describes a filter device for use during angioplasty or a therectomy having a filter assembly mounted on a flexible catheter or guidewire. The device contains a filter element such as a polyester cloth that can be closed using a drawstring. A rotating motion can be used to twist the stocking filter to aid in containing the embolic material. This device has a filter permanently attached to the guidewire and will therefore have much greater stiffness than a standard guidewire, thereby limiting its access to smaller vessels and vessels with difficult conformation. Ginsburg describes a catheter device with a filter at the end of a wire that is entered percutaneously from the downstream side of the lesion. This device is extremely limited by virtue of reduced or nonexistent access to the blood vessel in most cases downstream of the lesion. This device also shares the difficulties associated with having a permanently attached filter that will result in a stiff device.    Lefebvre describes in U.S. Pat. No. 5,810,874 a filter catheter that is intended for long periods of use. It has strips that form a filter that can be detached from the connecting means into a blood vessel. This device is not intended to capture and remove emboli, however. This device depends upon the natural thrombolytic mechanisms of the body to break down thrombus or emboli that have been collected by the filter.    In U.S. Pat. No. 5,846,260 by Maahs a modular blood filter device is described that can be introduced into a blood vessel. The device consists of an arterial cannula with a modular filter device. The frame may be expanded to an enlarged condition to capture embolic material in a mesh filter and collapsed to a contracted condition and removed from the vessel. The device appears to be very mechanical, stiff, and cumbersome, and would not have efficient application to interventional procedures in vessels that require a soft and flexible catheter.    Barbut describes a device and method for filtering emboli generated from a blood oxygenator in U.S. Pat. No. 5,769,816. The device has an insertion tube, an umbrella frame for positioning and maintaining a mesh filter in position, and a means for opening the umbrella frame. An inflatable balloon is attached to the mesh filter. This device is much too stiff and awkward to be used in a percutaneous interventional application that requires a flexible catheter and guidewire.    Gewertz (U.S. Pat. No. 4,969,891) describes a filter member attached to a wire member that is intended to enter the jugular vein and be advanced to the vena cava. The device is easily replaceable and removable at the end of the procedure. This device does not retrieve the thromboemboli but rather depends upon the body to break down the emboli. This is a temporary filter to remove large clots in the venous system. It could not work to retrieve emboli in an interventional procedure.    Molgaard-Nielson (U.S. Pat. No. 4,619,246) and Rasmussen (U.S. Pat. No. 5,133,733) describe filters that are placed into a blood vessel such as a vein to block emboli. The device of Molgaard-Nielson is a wire filter mesh attached to a wire and could be implanted and then moved within one week. Emboli that have been trapped are not intended to be removed from the vasculature. Rasmussen describes a filter that is normally deployed in the vena cava via a catheter in a collapsed form and expands outward to capture emboli. This device is intended for implant and does not provide for means to remove any collected emboli.